//返回数据集 public DataSet getdata() { SqlConnection con = new SqlConnection("server =.;database=sql;uid=sa;pwd=123"); DataSet ds = new DataSet(); SqlDataAdapter adap = new SqlDataAdapter("select * from student", con); adap.Fill(ds); return ds; } //返回字符串 public string getdata() { string s = ""; SqlConnection con = new SqlConnection("server =.;database=sql;uid=sa;pwd=123"); DataSet ds = new DataSet(); SqlDataAdapter adap = new SqlDataAdapter("select name from student", con); adap.Fill(ds); for (int i = 0; i < ds.Tables[0].Rows.Count; i++) { s = ds.Tables[0].Rows[i][0].ToString(); } return s; }
2.你返回的是dataset,就dataset.Table[0]这样变为dataTable,再用循环取出就变成字符串
//返回数据集
public DataSet getdata()
{
SqlConnection con = new SqlConnection("server =.;database=sql;uid=sa;pwd=123");
DataSet ds = new DataSet();
SqlDataAdapter adap = new SqlDataAdapter("select * from student", con);
adap.Fill(ds);
return ds;
}
//返回字符串
public string getdata()
{
string s = "";
SqlConnection con = new SqlConnection("server =.;database=sql;uid=sa;pwd=123");
DataSet ds = new DataSet();
SqlDataAdapter adap = new SqlDataAdapter("select name from student", con);
adap.Fill(ds);
for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
{
s = ds.Tables[0].Rows[i][0].ToString();
}
return s;
}
查询慢,还是优化sql语句,然后优化数据索引,实在不行优化数据结构。